1. Field of the Invention
This invention relates generally to power supply circuits, and more particularly is directed to an improved circuit for supplying stabilized operating DC voltages to a plurality of load circuits.
2. Description of the Prior Art
In an electric apparatus, such as television receivers, a radio receivers or the like, having circuits of which include transistors and other semiconductor devices and which are supplied with operating power from a commercial electric power lines, the limits of the endurable voltage of the transistors and other semiconductor device and/or desired reductions of power consumption, make it necessary to produce relatively low DC voltages from the AC voltage of the commercial electric power lines for application, as operating DC voltages, to the circuits in which the transistors and other semiconductor devices are included. In such cases, the AC voltage, for example, having a value of 100 volts, of the commercial electric power lines is usually stepped down by a power transformer, and the stepped down AC voltage is rectified to provide the relatively low DC operating voltages, for example, in the range of 12 to 50 volts. However, in apparatus using transistorized circuits a relatively large current flows through a power supply circuit, and therefore a relatively large power transformer is required with the result that the weight of the apparatus and the cost of the latter are undesirably increased.
To avoid the above disadvantages, it has been proposed to provide a circuit arrangement without the power transformer in which plural load circuits, for example, a horizontal deflection circuit and a vertical deflection circuit of a television receiver, are connected in series between output terminals of a rectifier circuit which produces a relatively high DC voltage at its output terminals by directly rectifying the AC voltage of the commercial electric power lines. In this case, the load circuits are supplied with respective relatively low DC voltages by dividing the high DC voltage obtained at the output terminals of the rectifier circuit. However, there is still the disadvantage that variation in the impedance of one of the load circuits causes variations in the low DC voltages applies to the respective load circuits, because the low DC voltages applied to the load circuits are obtained by dividing the high DC voltage in proportion to the respective impedances of the series connected load circuits.